html, body {
  height: 100%;
  margin: 0;
  padding: 0;
  background-color: black;
  display: flex;
  justify-content: center;
  align-items: center;
}

#canvas-container {
  margin: 50px;
  border: 2px solid white;
  box-sizing: border-box;
}

canvas {
  display: block;
}